none.
not applicable.
not applicable.
1. Field of Invention
The present invention relates generally to apparatus for straightening coil stock, and then feeding the straightened coil stock to a using station.
More particularly, the invention relates to apparatus provided with both straightening and feed rolls that are adapted to simultaneously engage the coil stock during material demand by the using station, and to simultaneously release the coil stock in the absence of material demand from the using station, and which, while suitable for other uses, is particularly useful in intermittently feeding coil stock to a punch press for ease of final positioning of the stock in the press.
2. Description of Prior Art
A conventional punch press line adapted to punch parts from coiled strip stock includes a reel that holds the coiled stock, a stock straightening mechanism that straightens the stock as it is drawn off the reel, and a feed mechanism that draws the stock from the straightener and feeds the straightened stock to the punch press.
A conventional coil stock feed mechanism includes a set of power-rotated feed rollers between which the strip stock is gripped, to pull the stock from the straightener and feed the stock to the punch press. For use with a punch press, the feed rolls are operative to alternately advance the stock in a selected length increment to the press, and then release the stock during the each punch cycle of the press.
A conventional coil stock straightening mechanism includes two sets of rollers between which the stock travels in a wave such that the stock cyclically flexes in alternating directions as it travels therethrough.
Precision stamping of strip stock requires the stock to be precisely positioned in the punch press during each punch cycle. This precision positioning is typically accomplished by punching a pilot hole in the stock at a first station, and actuating a tapered pilot pin at a second station through a pilot hole that was punched at the first station during a preceding press cycle for final positioning of the stock at the second station prior to punching of the desired part. During each cycle, the stock is feed into the punch press approximately one to two thousandths (0.001-0.002) inch short of the desired position by the feed mechanism, the feed mechanism releases the stock, and the tapered pilot pin draws the stock the additional 0.001-0.002 inch into the desired final position. After the desired part has been punched, the pilot pin is withdrawn, and the feed mechanism re-engages the stock to feed stock for the next cycle. Thus, operation of the feed mechanism is controlled in cyclic synchronization with the pilot pin operation of the punch press, or some other type of position control associated with the cyclic operation of the press.
Traditionally, the straightener and feed mechanisms are provided in separate units, with a loop of the coil stock therebetween. This loop of stock accommodates the difference in feed characteristics of the continuously acting straightener and the intermittently pulling feed mechanism. One such conventional arrangement is generally shown in Waddington U.S. Pat. No. 5,150,022.
In certain instances, the straightener and feed mechanisms have been combined into a single unit. This provides advantages including the elimination of the loop of material and an associated reduction of floor space requirements. The combined unit also simplifies set-up and control of the entire straightening and feeding process because the straightened material moves directly from the straightening rolls into the feed rolls and then into the die area of the punch press.
However, prior combined roll-type straightener and feed mechanisms present certain difficulties as regards the final positioning of the stock in the punch press. With the elimination of the loop of material, the integrated straightening mechanism resists movement of the stock into its final position as a result of the continuous tension applied to the stock by the straightener rolls. As a result, the pilot mechanism in the punch press must be adapted to overcome this tension as it pulls the stock into final position. Consequently, presses set-up for use with a combined straightener and feed mechanism typically experience wear of the pilot pin at an increased rate distortion of the material being fed, and are subject to loss in final positioning accuracy at a faster rate as compared with presses that are fed by a conventional feed mechanism that is separated from the straightening mechanism. Another drawback of prior combined straightening and feed mechanisms is that they are subject to loss in roll position and overall feed length accuracy.
Thus, it is apparent that there is a need for a combined straightening and feed mechanism that provides the benefits, but eliminates the above-identified disadvantages associated with prior combined straightening and feed mechanisms.
The general aim of the present invention is to provide new and improved combined feed and straightening apparatus adapted to feed precisely controlled length increments of coiled strip stock to a punch press in synchronization with the final positioning control system of the press, and which eliminates the continuously acting straightening roller tension on the stock of prior apparatus of the same general type.
A detailed objective is to achieve the foregoing by providing feed rollers and straightening rollers that simultaneously engage the strip material for straightening and advancing a length of stock to the punch press during a material demand cycle, and that simultaneously release the material at the end of each material demand cycle for final positioning in the press.
These and other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Briefly, a combined coil stock feed and straightening device includes a pair of feed rollers located on opposite sides of a feed path along which the strip stock is guided, and two sets of straightening rollers upstream of the feed rollers on opposite sides of the feed path.
Incremental movement of the coil stock through the device is accomplished by power rotating the feed rollers while the strip material is clamped therebetween, and stopping and separating the feed rollers to stop further powered movement of the strip material during operation of the punch press. The straightening rollers are adapted to separate from the coil stock simultaneously with the feed rollers for ease of final positioning of the stock in the press.
In preferred embodiments, one of the feed rollers is rotated on a fixed axis in relation to the feed path, and the other feed roller is moveable toward and away from the fixed feed roller between a material gripping position and a material release position. Similarly, one of the sets of straightening rollers rotate on fixed axes in relation to the feed path, and the other set is movable toward and away from the fixed set for movement between a material engaging-straightening position and a material release position.
A pair of operators, responsive to fluidic control signals, effect synchronized movement of the movable feed roller and the movable set of straightening rollers between said positions, and associated pilot release valves are operable to supply the fluidic control signals in response to material demand signals from the punch press.